Cognitive Disability and Moral Status

First published Fri Jul 6, 2012

Why are cognitive disability and moral status thought to be
sufficiently connected to warrant a separate entry? The reason is that
individuals with cognitive disabilities have served as test cases in
debates about the moral relevance of possessing such intellectual
attributes as self-consciousness and practical rationality. If a
significant portion of human beings lacks self-consciousness and
practical rationality, then those attributes cannot by themselves
distinguish the way we treat cognitively developed human beings from
the way we treat non-human animals and human fetuses. If we cannot
experiment on or kill human beings who lack those attributes, then the
lack of those attributes alone cannot be what justifies animal
experimentation or abortion.

For the most part, the philosophers who have considered these claims were
not primarily concerned with the treatment or moral status of
cognitively disabled human beings—they sought to challenge
existing practices toward fetuses or animals, or the rationales for
such practices. But those claims have significant practical
implications for cognitively disabled human beings. If the
justification for treating living beings in certain ways does
rest to some extent on their possession or lack of intellectual
attributes, then it may be acceptable to treat cognitively disabled
human beings in ways that it would be unacceptable to treat cognitively
nondisabled humans. This implication, a kind of philosophical blowback
from the debates on animal rights and abortion, has become the subject
of sustained controversy in applied ethics.

Philosophers who question the moral status of human beings with the
most significant cognitive disabilities often compare them to animals
claimed to have similar or greater cognitive abilities (McMahan 1996,
2002, 2009; Singer 1993, 2009; and Wilkinson 2008 in Other Internet
Resources). Some critics find these comparisons unnecessary and
offensive (e.g., Carlson 2009; Carlson and Kittay 2009). The
philosophers who make such comparisons emphasize contrasts like the
following: Vast numbers of chimpanzees and other “higher”
primates are used in painful and often lethal research for the benefit
of human beings. Although there are strong objections to specific
primate research programs and research on specific primates, there is
broad agreement that most primate research is acceptable if it has the
potential to contribute significantly to human health, and if the
harms and risks to the animal subjects are minimized. In contrast,
cognitively disabled human beings no better able than those primates
to understand the aims of the research or to consent to participation
cannot be enrolled in potentially harmful research unless they are
likely to benefit, the risk of harm is negligible, and their legal
representatives consent to their
participation.[1]

The debate over the moral status of individuals with the most severe
cognitive disabilities also raises difficult methodological issues
concerning the reliance on intuitions, convictions, and considered
judgments in assessing moral arguments. Some philosophers would deny
that any argument should persuade us to abandon our conviction that it
would be terribly wrong to subject a human being cognitively incapable
of consent to painful and dangerous experimentation of no possible
benefit to him (e.g., Kittay 2008). Others would insist that even such
firm convictions cannot be immune from critical scrutiny,
especially if they appear to conflict with other deeply held
convictions (McMahan 2007). Still others would accord such convictions
no presumptive weight or authority (Singer 2005).

Finally, in addressing the moral status of cognitively disabled
humans in a separate entry, rather than in a general entry on
disability, we are not endorsing a questionable
“exceptionalism” about cognitive disabilities—a
view that regards them as fundamentally different from other kinds of
impairment (see Related Entries below). Our reason for limiting
ourselves to cognitive impairment is dialectical: there is currently no
debate about the moral status of individuals with non-cognitive
disabilities. We know of no serious philosopher who argues that people
who cannot see, hear, or use their legs, or who experience frequent
depression or auditory hallucinations, have lower moral status than
people who lack these disabilities. Admittedly, the consensus may
be superficial. Some philosophers who claim to treat adult human beings
with physical or psychiatric disabilities as having the same moral
status as nondisabled adult humans also take positions that other
philosophers see as inconsistent with a commitment to equal moral
status. One notable example is Rawls' (1971) exclusion of people
with physical disabilities from the Original Position on the assumption
that they are not fully cooperating members of society. Another example
is the defense of “quality adjustment” in allocating scarce
healthcare resources, which discounts the life-years of people with
disabilities to reflect their supposedly lower quality of life
(Williams 1987). Whether or not these positions are
consistent with the recognition of full moral status, their proponents
insist that they are; they do not deny, or attempt to argue against,
the equal moral status of people with physical or (most) psychiatric
disabilities. By contrast, the moral status of human beings with
cognitive disabilities has become a subject of intense debate among
philosophers, applied ethicists, and disability scholars (for a recent
discussion, see Carlson and Kittay 2009).

We will proceed as follows. We will first characterize the human
beings who are the subject of the debate on moral status—those
with what we will call “radical cognitive disabilities.”
After discussing the ways in which human beings are classified as
cognitively disabled, we will describe this narrower category of human
beings whom the debate concerns—a set of individuals stipulated
to exist rather than classified by empirical procedures. We will note
the difficulty of separating claims about such stipulated individuals
from claims that some actual human beings satisfy that
stipulation. Next, we will characterize the concept of moral status,
describing its structure and function. We will then outline the
principal differences in how that concept is understood, particularly
its “inclusion criteria”—the criteria for ascribing
what we will call “full moral status,” the status
attributed to cognitively nondisabled adult human beings. (In calling
that moral status “full,” we do not intend to take sides
in the debates over whether there can be any higher moral status.) We
will identify one family of moral-status accounts—those basing
possession on individual attributes—as the primary, though not
the exclusive, source of the challenge addressed in this entry: the
claim that some human beings lack full moral status. After outlining
those accounts, we will review several ways of meeting the challenge:
1) basing full moral status on individual attributes shared by a
greater proportion of human beings; 2) adopting secondary grounds for
the possession of full moral status—by “courtesy” or
by “proxy”; 3) rejecting individual attribute accounts in
favor of accounts that base the full moral status of all human beings
on their species membership or their broader humanity.

There is, not surprisingly, disagreement about how to define cognitive
or intellectual disability. (We will use these terms interchangeably,
ignoring, unless specifically relevant, their apparent differences in
breadth and emphasis.) There are competing psychometric and functional
definitions, based respectively on standard deviations from the mean
score on intelligence tests and on “significant limitations both
in intellectual functioning and in adaptive behavior, which covers many
everyday social and practical skills” (American Association of
Intellectual and Developmental Disabilities, 2011). For this
entry, we will consider individuals defined as cognitively disabled in
functional terms, because our interest is in the moral relevance, if
any, of the absence or substantial limitation of critical cognitive
functions. We will not assume that, or examine whether, individuals
with psychometrically-defined “severe” or
“profound” intellectual disabilities are functionally
disabled in this way.

As noted, this entry will focus on human beings with “radical
cognitive
disabilities”[2]
— disabilities in
intellectual function and capacity that limit or preclude the
development of one or more attributes believed to confer full moral
status. Among those attributes are the consciousness of oneself as a
temporally-extended being; practical rationality—the capacity to
govern one's actions by reasoning about how to act; and the
capacity to make and respond to moral demands. (We will often
abbreviate the list to “self-consciousness or practical
rationality” without making any assumptions about the centrality
or relationship of the two attributes.) These attributes, as well as
others held to be required for full moral status, may be possessed by
different subsets of human beings, and the relationship among such
attributes is a matter of considerable dispute. This dispute, however,
is best deferred to a fuller treatment of the grounds of moral status;
we will discuss them only to the extent that they bear on the moral
status of human beings with significant cognitive disabilities.

The category of “radical cognitive disability” is
stipulative. We do not start with the assumption that any specific
human being falls into that category, or even that some human beings
do. Eva Kittay (2005) has argued that there is no reason to assume that
any human beings are radically cognitively disabled, in the sense we
are using the term. Jeff McMahan (2009) has countered that the
existence of such human beings is very likely: given the continuous
nature of fetal and infant neurological development, it is very likely
that some human beings are radically disabled because their development
has ceased or been interrupted at points where they have not yet
acquired morally relevant capacities. Even if McMahan's
“existence argument” for radical impairment is correct,
however, it does not remove the daunting uncertainty of attributing
radical cognitive impairment to any actual human being.

This uncertainty arises in part from a lack of clarity and consensus
about what would count as adequate evidence of self- and
other-awareness and practical rationality. To resolve that question, it
is necessary to confront not only interpretive ambiguities in making
inferences about the content of other minds, but conceptual issues
about what it means to possess critical cognitive functions. Similar
issues are raised in the debate about animal consciousness (see the
Entry on animal consciousness),
but there is also disagreement about whether the
kinds of evidence adduced for and against the cognitive capacities of
animals are equally relevant in assessing the cognitive capacities of
human beings (Kittay 2005; McMahan 2002, 2005, 2008).

The primary reason for restricting the entry to radical cognitive
disability, like the reason for restricting it to cognitive disability,
is dialectical. Few contemporary philosophers would deny that human
beings with mild or moderate cognitive disabilities have the attributes
required for the moral status enjoyed by cognitively normal human
beings—for what we call “full moral status.”
Philosophers who see self-consciousness and practical rationality as
necessary for full moral status generally recognize that mildly and
moderately disabled humans possess those attributes, and possess them
to the extent necessary to reach the threshold set by their accounts of
full moral status (see Sec. 2.1).

By stipulating a category of human beings with radical cognitive
disabilities, we seek to avoid difficult empirical issues about the
extent to which individuals classified as having serious cognitive
disabilities actually lack the psychological functions held to confer
moral status. Even the most direct assessments of these functions may
fail to recognize nonstandard, particularly nonverbal, forms of
cognitive functioning. And with the possible exception of extreme cases
like anencephaly, there are formidable difficulties in inferring a lack
of cognitive capacity from a lack of specific behavior or brain
activity.

We recognize that there are objections to the use of stipulation to
sidestep these difficult empirical issues. Disability scholars insist
that philosophers must recognize that the terms they use will
inevitably be taken to refer to actual human beings, so that they
cannot stipulate away concerns about hurt and misinterpretation
(Kittay 2005; Wong 2007). Moreover, the prevalence of individuals who
actually satisfy their stipulations has relevance to morally
significant policy issues, such as the costs and benefits of more
inclusive educational practices. Nevertheless, we will rely on the
stipulation that we have made about radical cognitive disability, in
part because the assumption that some human beings are radically
disabled is shared by many of those who argue for the full
moral status of all human beings.

We will discuss only radical cognitive disabilities that are
congenital or early-onset. The question of how moral status is
affected by the loss of important cognitive functions is a
distinct one, both for those who believe such functions confer moral
status and those who do not. Concerning the former, the question is
whether moral status can survive the loss of the functions on the
basis of which it was conferred. For those who deny that moral status
requires the possession of those functions, their loss may still raise
important questions about personal identity, and about the
first-person authority of the earlier, nondisabled self over the
later, disabled self. The treatment of “once-competent”
individuals in minimally conscious states, or with severe dementia,
thus raises distinct issues about the impact of psychological
discontinuity or loss of mental function on the relationship of human
individuals to their past or future selves. There has been a
protracted controversy, and a large literature, on these issues
(Dresser 1995; Dworkin 1994; Stone 2007); they deserve separate
discussion.

“Moral status” is not part of the shared vocabulary of all
ethical theories. An act utilitarian, for example, has no more use for
that concept than for “respect,” “rights,” or
“inviolability.” For a theory that accorded weight to
beings only in proportion to the utility they enjoyed or produced, the
concept of moral status would be relevant only in the indirect sense
that its use would affect aggregate utility in various ways. For
example, the negative utility that might result from denying some human
beings full moral status might support a policy of treating all human
beings as if they had full moral status
(see Sec. 4). On such
a theory, the most salient moral property of an individual is her
capacity to occupy states that can be characterized as
“good” or “bad,” the most obvious being
pleasure and pain. The possession of such a capacity gives an
individual a morally considerable interest in occupying or avoiding
such states. Moral considerability is: 1) continuous, in that the
degree of moral considerability that a being possesses varies in
proportion to the strength, character, and number of its interests; and
2) asymmetrical, in the sense that a being might have moral claims on
others without others having moral claims on it.

When non-utilitarian philosophers discuss “moral status”
of a type of being, they are generally using a more categorical notion
than moral considerability. They generally understand moral status as
a threshold concept and a range concept. Beings that fall below a
minimum level—the threshold—of a status-conferring
attribute like rationality lack a certain kind of moral status
despite possessing the attribute to some degree. And all beings that
fall within the “range”—that reach the threshold
level of the attribute—have the same moral status regardless of
how far they exceed that threshold. (The term “range
concept” comes from Rawls; his example is of points within a
circle, all of which are equally “inside” despite varying
distances from the circumference.) More controversially, moral status
is sometimes regarded as symmetrical: a being must be able to have
moral claims made on it (and hence be capable of responsibility) as
well as being able to make moral claims on others. A symmetry
condition would exclude any human being lacking the capacity to have
moral claims made on them—not only individuals with radical
cognitive impairments, but infants and young children as well.

Not all writers on moral status treat it as both a threshold and
range concept. Both features of the concept have been challenged, and
the concept itself has been criticized as hierarchical and elitist
(Birch 1993). Several philosophers have argued for treating moral
status as a matter of degree, so that a being's moral status
varies proportionately with its morally-relevant attributes (Perring
1997; DeGrazia 2008). These proposals avoid uncomfortably sharp
dichotomies, but they have a revisionary character. Even if commonsense
morality recognizes some gradations in moral status, well-established
social practices such as animal research assume discontinuities.
Moreover, even if common sense could be reconciled to gradations below
the threshold (which would thereby become less of a threshold), it
would balk at recognizing gradations above it, thereby abandoning moral
status as a range concept.

More comprehensively, Mary Ann Warren has proposed a multi-criterial
account of moral status, in which it is neither a range nor a threshold
concept. For Warren, the moral status of a being varies with the degree
that it possesses the status-conferring attribute
(Warren 1997).[3]
But Warren maintains that “full moral status” is both a
threshold and a range concept; beings with moral agency enjoy the same,
highest moral status regardless of the degree to which they possess the
attributes needed for moral agency. As noted earlier, we will use the
term “full moral status” to refer to the moral status that
is generally accorded to cognitively nondisabled human adults, without
assuming that there can be no higher status. “Full moral
status” is thus roughly synonymous with “personhood”
as that term is used in debates about whether fetuses, or higher
primates, are persons.

The issue of moral status, and which beings have full moral status,
has become important because of its bearing on the rights and
treatment of those beings. “Moral status” and “full
moral status” are not intended as honorifics; their ascription
to a being entails that it enjoys rights that other beings, lacking
that status, do not. The particular rights entailed by full moral
status may, however, differ on different moral theories. Two theories
with the same concept of moral status and the same criteria for
assigning it (see Sec. 2.2) may associate
full moral status with different rights or rights of different
strength. One theory might, for example, hold that beings with full
moral status may never be used as mere means, whereas another might
hold that they may be so used in specific emergencies. There is,
though, only partial independence between the formal character of and
criteria for moral status, on the one hand, and the rights entailed by
such status, on the other. For example, it would seem implausible for
a theory to recognize a categorical notion of moral status while
rejecting any notion of rights. An account of moral status need not
deny all rights to beings falling below the threshold it sets; they
will merely lack the same package of rights possessed by beings above
that threshold.

One philosopher (Sachs 2011) has argued that claims about moral
status are unnecessary and confusing, because the debate is really
about the specific attributes needed to justify or ground specific
rights. Although moral status claims may well obscure more often than
they enlighten, they do not merely concern the grounding of specific
rights in specific attributes. First, as just noted, theories that
share the same criteria for full moral status may differ in the rights
they associate with that status, and vice-versa. The debate over moral
status thus appears to raise issues besides the grounding of specific
rights. Second, some of these distinct issues concern the threshold and
range features of the concept of moral status: how small differences in
morally-relevant attributes—those placing a being above or
below the threshold—can result in significant differences in
the package of rights and immunities a being possesses; how all
cognitively normal humans can have the same package of rights and
immunities despite differing greatly in the attributes that place them
above the threshold. Those who defend the standard concept of moral
status seek a theory to underwrite its range and threshold features;
those who attack it argue that no plausible moral theory could do
so.

The central distinction in the debate over the full moral status of
human beings with radical cognitive disabilities concerns the type of
attributes on which moral status is based. Most of those who deny or
question the full moral status of all human beings insist that moral
status must be based exclusively on attributes or properties of the
individual; those attributes must be identifiable by a biological or
psychological inventory of that individual, with no reference to the
biological or social environment it inhabits. For example, it would be
possible to assess an individual's self-consciousness or
practical rationality knowing nothing about its fellow creatures
(although the assessment itself might have to be done by self-conscious
and practically rational creatures). In contrast, we could not
ascertain an individual's species membership or social
relationships without knowing a great deal about the world it
inhabited. We will call accounts based solely on individual attributes
“individually-based”; we will label accounts
“group-based” as those based on facts about the
individual's membership in a biological or social group, or her
relationship with other members of that group. Those facts may concern
the individual's biological origins, the typical or average
characteristics of a biological or social group to which she belongs,
or her actual relationships with other individuals. Although some
individually-based accounts concern an individual's capacity or
potential to form relationships of certain kinds with other
individuals, it is that capacity or potential which confers moral
status, not the existence of such relationships.

Those who insist that moral status must be based on an
individual's own attributes, that it cannot depend on the
accidents of birth or the vagaries of biological classification, are
also likely to insist that an individual's claims on others
cannot depend on whether those others happen to be members of the same
species or communities. In this view, full moral status must not only
be independent of external circumstances, but must be universally
recognized. Although some group-based accounts may require that a
being's full moral status be universally recognized, others see
full moral status as group-relative (see Sec. 5.1).

In comparing accounts of moral status, it is important to note two
possible differences between such accounts. First, they may propose
different conditions as sufficient for full moral status. Some
accounts, for example, claim that membership in the human species is
sufficient for that status. Second, they may offer different
explanations of how the satisfaction of those conditions grounds or
warrants full moral status. For example, even if being a Homo sapiens
suffices for possessing that status, there may be different rationales
for why it is sufficient: 1) because it is in the nature of
Homo sapiens to be rational, or because the rational nature of
the species requires respect for all of its members, rational or not;
and 2) because members of the same species owe a duty of partiality to
each other, regardless of their individual attributes. The two accounts
ground moral status in the same relational property—membership
in the human species—and they make membership a sufficient
condition for full moral status. But they use the fact of species
membership differently in justifying moral status. They might also
associate different rights with full moral status, in accordance with
their different ways of grounding it. And, as discussed in
Sec. 4, they
may have different implications about who is required to recognize or
respect an individual's status.

Individually-based accounts generally take cognitively normal adult
human beings as their paradigm and pick out one or more of their
attributes as sufficient for the moral status they
enjoy.[4]
These accounts identify overlapping
clusters of psychological and cognitive
attributes—self-consciousness, awareness of and concern for
oneself as a temporally-extended subject; practical rationality,
rational agency, or autonomy; moral responsibility; a capacity to
recognize other selves and to be motivated to justify one's actions to
them; the capacity to be held, and hold others, morally
accountable. These attributes pick out different subsets of human
beings. Some self-conscious humans, for example, may lack the capacity
to be held morally accountable. But individually-based accounts may
differ less in the range of beings to whom they accord full moral
status than in the ways they regard those attributes as grounding that
status.

One approach holds that psychological attributes confer moral status
by virtue of the interests to which they give rise. This approach
treats psychological attributes as the basis of interests that we have
a prima facie obligation to advance, or at least not to
thwart—an obligation whose strength varies with the strength and
other features of those interests. The capacity to feel pain grounds
an obligation to avoid its infliction; the capacity to anticipate and
dread as well as feel pain may ground a stronger obligation. But if
additional psychological capacities merely increased the strength of
the interest, and the corresponding obligation to advance or not
thwart it, an interest account would not yield a clear threshold for
full moral status (McMahan 2002). More categorical interest-based
approaches ground moral status on the capacity to experience oneself
as temporally-extended beings whose lives can go better or worse
(Singer 1993; Tooley 1983) or to value one's own existence (Harris
1985; Newson 2007). Individuals having such capacities can care about
and value their future lives in a way that individuals lacking
self-consciousness cannot, giving them a qualitatively weightier
interest in those lives (McMahan 2002). Whether or not such capacities
can account for the threshold and range features of full moral status,
their adoption as criteria appears to deny that status to human beings
with the most significant cognitive impairments.

A second approach, derived from or inspired by Kant, sees moral
status in terms of the respect demanded by the possession of one or
more attributes, such as autonomy or rational agency (e.g., Korsgaard
1996). This approach regards the possession of an autonomous will as
conferring dignity and demanding respect, so that a being with such a
will must not be treated as a mere means, but as an end. This Kantian
conception of full moral status is often regarded as a paradigm, in
identifying an attribute that does not vary
continuously,[5]
and whose possession appears to have
clear moral implications. The threshold for moral status set by many
Kantian accounts is a high one. If those accounts regard the capacity
for autonomy as the threshold for full moral status, and if they
understand that capacity as grounding moral status in moral
responsibility, then a since “there is nothing for which we
would hold human infants or severely cognitively disabled adults
morally responsible, it is argued, such humans must lack Kantian moral
status” (Kain 2009, 66).[6]
Even if humans did not need to be held morally responsible to
enjoy full moral status, many would still lack the capacity for
autonomy that seems essential on any Kantian account.

A third approach, associated with contractualism, sees moral status
in terms of the attributes needed for membership in a moral community,
or for participation in relationships of mutual recognition
and
concern.[7]
It is the capacity for forming such relationships, not their actual
formation, which grounds full moral status. A cognitively normal human
being would have such status even if he were abandoned on a desert
island. This approach, the most clearly symmetrical, treats certain
attributes as necessary for moral status not because their mere
possession generates moral obligations, but because they are requisites
for the kind of relationships in terms of which the proponents of this
approach understand moral obligations. This requirement may appear to
give cognitive and psychological attributes a more instrumental role
than they are assigned by the second approach. It's not that
their mere possession demands respect, but that they enable their
possessors to form relationships of which mutual respect is an integral
part.

Though relationship- or community-based accounts differ conceptually
from respect-based accounts, they differ little in practical terms.
They will identify different human beings as having full moral status
only if humans can have the cognitive or other psychological capacities
held to be necessary for respect but lack the empathy or motivation
held to be necessary for membership in a moral community (or
vice-versa). For example, a moral-community account might exclude
psychopaths. But so might a respect-based account, if it denied
psychopaths autonomy because they lacked the capacity to be motivated
by a sense of duty, or more broadly, a capacity to recognize and act on
moral reasons (see Shoemaker 2007). A respect-based account might also
exclude psychopaths if it attributed their moral deficits to severe
disabilities in practical reason. Relationship- or community-based
accounts would, like Kantian ones, appear to set a very high threshold
for full moral status. The greater the moral accountability demanded by
the relationship or community, the more difficult it may be to claim
that human beings with radical cognitive impairments are capable of
participation.

One challenge for all of these accounts is to identify an attribute
or attributes that can explain, or at least be reconciled with, the
threshold and range features of the prevailing concept of moral status.
The difficulty presented by a threshold is that it imposes a moral
discontinuity over psychologically continuous attributes. In contrast
to the possession of a soul or a divine spark, practical rationality
and moral accountability, and most other individual attributes claimed
by contemporary accounts to ground moral status, appear to come in
degrees. Looking at the development of an infant, for example, the
acquisition of these attributes appears to be gradual, even if the rate
of growth is uneven. And yet our judgment of moral status appears
categorical—an individual either has full moral status or lacks
it. The categorical character of moral status is also clear above the
threshold. We do not think that the more highly intelligent, more
deeply self-conscious, or more fully autonomous among us have a higher
moral status than the rest, even those close to the threshold. The
challenge of justifying the range feature of moral status is closely
related to the challenge of justifying the threshold—why should
differences above the threshold be morally insignificant when the
differences marked by the threshold are so significant?

If full moral status is determined by the possession of any of the
cognitive attributes discussed in the last section, then that status
will be enjoyed by some non-human animals and—more
problematically—almost certainly lacked by some human beings.
Most proponents of individually-based attribute accounts welcome the
implication that we cannot justify prevailing disparities between our
treatment of “higher” animals and cognitively disabled
human beings, and many argue that those disparities are better reduced
by raising our standards for the former than by lowering them for the
latter:

The optimal point of convergence … requires that
traditional beliefs about animals be more extensively revised than
traditional views about the severely retarded. (McMahan 2002,
230)

But full convergence, as McMahan recognizes, would have
disturbing implications even if it were achieved entirely by upgrading
the treatment of nonhuman animals:

[T]he preservation of the
traditional view [that it is seriously wrong to kill an anencephalic
infant] will commit us to the conclusion that it is seriously wrong to
kill an animal that altogether lacks the capacity for consciousness.
And this is unacceptable. (2002, 230)

Convergence at a significantly lower level would have equally
unacceptable implications. For example, it would permit the use of
radically impaired human beings (at least those lacking special ties
to cognitively normal human beings) in any research, however harmful,
for which the use of animals with comparable cognitive capacities was
permitted. Any view about moral status that aspires to reflective
equilibrium with our deeply held moral convictions must address the
abhorrence with which most thoughtful people would regard the
practical implications of treating humans with radical cognitive
disabilities as having even slightly lower moral status than the rest
of us.

A variety of approaches seek to address that abhorrence: by
identifying criteria for full moral status that include a wider range
of humanity (Sec. 4.1); by expanding
the ways in which an individual
can possess or achieve full moral status without denying the primacy of
individual attributes (Sec. 4.2);
and by shifting from individually-to group-based accounts of
moral status (Sec. 5).

Several accounts identify attributes, such as the capacity to value
or care, which are shared by a greater proportion of human beings than
self-consciousness, practical rationality, autonomy, or moral
accountability. These accounts seek to recognize the full and
equal moral status of all, or almost all, human beings, including
children, and of adults with significant cognitive and psychological
disabilities. Among the more inclusive criteria proposed are the
capacity to communicate, or for minimal communication with other humans
(respectively, Berube 1996; Francis and Norman 1978); to value or
care (Jaworska 1999, 2007); to give and receive love (Kittay 1999);
and to engage in relationships characterized by reciprocity of care
(Mullin 2011). These criteria are attractive because they identify
attributes that may offer a more intuitively appealing foundation for
moral status than practical rationality or self-awareness, and because
they reduce, to varying extents, the proportion of humans excluded from
personhood. But because they arguably still exclude some humans, and
include some non-human animals, they will be unacceptable to some
philosophers. Moreover, these alternative attributes do not
resolve, but merely relocate, the problem of accounting for the
threshold and range features of full moral status.

One attribute—the potential for any other individual
attribute held to suffice for full moral status—comes much
closer to full inclusion (Kumar 2008). But it faces three formidable
problems. As Joel Feinberg (1986) famously argued, the fact that
someone has the mere potential for an attribute does not warrant
treating him as if he actually possessed it. If potential has moral
significance, it cannot be directly inferred from the moral
significance of that which it actualizes. Further, some human beings
never have the potential for any individual attribute held to suffice
for full moral status, in any sense of “potential” that
would distinguish them from many non-human animals (McMahan 2008,
91–92). This raises the problem of determining what it takes to
have the “potential” for an attribute. The claim that
someone has potential is a counterfactual: in some other
circumstances, perhaps a later life-stage of the individual, the
person would have the attribute. This brings in difficult questions
about the scope of such counterfactuals. On a broad enough construal,
every living being has the potential to develop the relevant
attributes in a sufficiently different possible world, and so has full
moral
status.[8]

A second general way of accommodating the powerful intuitions about
the full moral status of all human beings is to recognize alternatives
to the actual possession of the status-conferring attributes. One
version of this approach treats human beings with radical cognitive
disabilities as, in effect, capable of acquiring the necessary
attributes by proxy, through their relationships with other human
beings. Thomas Scanlon (1998), for example, affirms the full moral
status of all human beings while basing full moral status (“the
requirement of justifiability”) on the individual capacity for
“judgment-sensitive” attitudes. Although he recognizes that
radically-disabled humans lack those attributes, he suggests that they
can acquire them vicariously, through trustees:

The tie of birth gives us good reason to want to treat [human beings
lacking the capacity for judgment-sensitive attitudes] “as
humans” despite their limited capacities. Because of these
limitations, the idea of justifiability to them must be understood
counterfactually, in terms of what they could reasonably reject if they
were able to understand such a question. This makes the idea of
trusteeship appropriate in their case, whether it is appropriate in the
case of nonhuman animals or not. It also indicates a basis on which
such a trustee could object to proposed principles. Severely disabled
humans have reason to want those things that any human being has reason
to want, insofar as those are things that they are capable of
benefiting from. (185–186)

Scanlon himself may understand trusteeship merely as a way of
realizing or respecting the full moral status of human beings with
radical impairments, a status based on “the ties of birth.”
Other philosophers, however, suggest that trusteeship can secure full
moral status by helping to satisfy criteria that could not otherwise be
met. Thus, Francis and Silvers (Francis 2009; Silvers and Francis
2009) argue that cognitively normal human beings can function as
“mental prostheses” for radically impaired ones:

[A]s a prosthetic arm or leg executes some of the functions of a
missing fleshly limb without being confused with or supplanting the
usual fleshly limb, so, we propose, a trustee's reasoning and
communicating can execute part or all of a subject's own thinking
processes without substituting the trustee's ideas as if it were
the subject's own. (485)

Francis and Silvers do not claim that the moral status of human
beings with the most significant cognitive impairments could rest on
such trusteeship, or on the potential for it. But it is useful to
consider two challenges in developing their proposal in this manner.
The first is the question of authorship or authenticity: It is not
clear how a trustee's reasoning could be said to
“execute” all, as opposed to part, of “a
subject's own thinking.” It is not clear how the thinking
can be the subject's if it was wholly executed by a trustee
(Wasserman and McMahan forthcoming). The second challenge, which
the notion of mental prostheses shares with Scanlon's notion of
the vicarious expression of judgment-sensitive attitudes, is that it is
not clear why such functions could not be undertaken for nonhuman
animals—a possibility Scanlon leaves open in the above passage.
If it could be, then the potential for such representation would
ground the moral status of vast numbers of primates and other mammals.
To close the floodgates, it would seem necessary to argue that this
representation was less feasible for intelligent animals, even
domesticated ones, than it was for radically impaired human
beings. Clearly, an argument would be needed that the
counterfactual exercise Scanlon prescribes is more practicable or
comprehensible for our fellow humans than for even the most intelligent
animals. In Francis and Silvers' terms, it would be far more
difficult to fashion a mental prosthesis for the latter.

A
proxy approach also raises the difficult question of how the trustee
can acquire the moral and epistemic authority to speak for an
individual with radical cognitive disabilities. Legal systems assign
trustees or guardians to represent the “best interests” of
individuals too immature or impaired to make, or to have made, their
own judgments. But it is not clear how someone gets
“appointed” as a trustee for purposes of securing moral
status. Moreover, even those closest and most committed to an
individual with radical cognitive impairments may find it hard to
discern his interests, and distinguish them from their own
“judgment-sensitive” attitudes.

Another way of accommodating strong convictions about the full moral
status of all human beings bases that status on actual relationships
between cognitively normal and radically-disabled human beings. Because
of their duties of partiality, the parents and siblings of radically
impaired individuals must treat them as if they had full moral status.
To the extent the necessity is not merely psychological but moral, this
becomes in part a group-based account, with an extreme form of
agent-relativity: for close family members and no one else, radically
disabled humans actually have full moral status. But because of the
full moral status of those close family members, other human beings
must respect their obligation to treat their disabled relatives as
having full moral status. They do not, however, have to assume that
obligation themselves. Some proponents of individually-based accounts—McMahan, for example—appear to take this view. In contrast,
some of the group-based accounts in the next section hold that the
“tie of birth” requires all cognitively nondisabled human
beings to accord full moral status to every other human being,
regardless of their relationship. A weaker version of the derivative or
courtesy position does not claim that a human being with radical
cognitive disabilities actually has full moral status even for close
family members, merely that they must treat her as if she did.
This reduces somewhat (but does not eliminate) the disparity between
family members and third parties, but only by downgrading the moral
status of radically-impaired humans even for their most significant
others.

For some philosophers, either version of this view is
unsatisfactory, for two related reasons. First, it is too narrow, since
it denies the full moral status of all human beings to and for each
other. Second, it is too contingent—a human being with radical
cognitive disabilities owes even his partial equality to the existence
of certain relationships. If his parents and other relatives abandon
him or die, he has only a very tenuous claim to being treated by the
rest of humanity any better than a non-human animal with similar
attributes.

Yet another approach to accommodating the conviction that every
human being has full moral status would be epistemic, calling for the
adoption of a strong, even “irrebuttable” presumption of
full moral status for all human beings. This approach is based on the
difficulty of assessing the cognitive potential of human beings, the
powerful tendency to underestimate the capacity and potential of human
beings with any degree of cognitive abnormality, and the terrible cost
to individuals who warrant but are denied full moral status. This
approach can be regarded as rule-consequentialist, in requiring that we
sometimes disregard our case-specific judgment because of the high
probability and substantial costs of error. But it has appeal for many
who reject rule-consequentialism as a general approach. At the same
time, this rationale for full moral status may seem uncomfortably
grudging and contingent. It appears to imply that, with sufficiently
accurate assessment tools and sufficiently reliable assessors, we could
deny moral status to many human beings whom we now are constrained to
treat as having it. Moreover, their exclusion would represent moral
progress.

Such a presumption of full moral status for humans with radical
cognitive disabilities could be given a more robust justification. That
justification would treat biological differences, species norms, and
“ties of birth” not as providing independent grounds for
full moral status, but as providing very strong reasons for presuming
it. Perhaps part of the reason we presume this is epistemic, because it
is so difficult to conclude that individuals who look human really lack
human capacities. But that is not the whole explanation. When
cognitively nondisabled humans encounter another being with human
appearance, they customarily respond to that being in ways they do not
to non-human animals; they use distinctive gestures, facial expression,
touch, speech, and other behavior. Such responses assume a capacity for
reciprocal exchange that may not always be present. But even when it is
not, those responses are not idle gestures. They may enable
communication, and provoke cognitive and social development, that would
otherwise not occur. Family members, friends, professionals, and
scholars who work with people who have cognitive disabilities report
that the more time they spend with individuals who initially seemed
unable to communicate or respond meaningfully, the more they
could discern about their interests, desires, and moods (Brown and
Gothelf 1996; Goode 1994). Indeed, those people often display
species-typical preferences in clothing, food, socializing, and other
activities. In sustained interaction with nondisabled humans who treat
them as members of the same moral community, cognitively disabled
individuals develop socially and psychologically along the lines of
other human beings. Treating people with cognitive disabilities as
though they had potential for typically human desires and responses,
then, can thus become self-fulfilling. This offers a pragmatic (and
consequentialist) justification for a presumption that all human beings
have full moral status: not merely because of the terrible costs of
mistakenly denying that status, but because treating fellow human
beings as capable of joining our moral community makes it more likely
that they will be able to do so.

This proposal does not claim that such treatment could never be
effective if directed toward a dolphin or chimpanzee. But we have
stronger reasons to treat our fellow human beings this way, however
significant their cognitive disabilities. Our shared embodiment and
genetic endowment facilitate our treating them as having the capacity
or potential for typical human interaction and activity, and make it
likely that they will be more responsive to such treatment than a
non-human animal with similar cognitive abilities. Other intelligent
beings, differently embodied than we are, would have the same reasons
to treat their fellow beings this way. In recognizing
such a limited partiality, we do not treat species as having a moral
significance akin to that of families or even nations. Nor, clearly, do
we assume that human beings in particular have special moral
status.

Despite its resolute optimism, this proposal still excludes some human
beings from full moral status. It assumes a minimum level of social
responsiveness which is almost certainly lacking in human beings with
anencephaly, and perhaps lacking in human beings with other extreme
cognitive impairments. Yet in its pragmatic justification of a limited
partiality towards members of the same species, it sets the stage for
views that give a more central role to species membership.

A number of philosophers have argued for the full moral status of
all human beings, without seeking to identify any intrinsic attribute
possessed by all humans that would ground that status. These
philosophers can be loosely divided into two groups. Those in the first
group regard membership in the species Homo sapiens as
sufficient for full moral status and ground that status in a
species-based attribute (See Sec. 2.2).
For some philosophers in this first group, all homo sapiens belong to a kind whose nature or norm it is to
possess rationality or similar attributes. For others, all homo sapiens are connected through “ties of birth” to
other human beings. For the former, any being of a kind whose nature
it is to be rational, etc. has full moral status; for the latter, any
human related by birth to other human beings has full moral
status. Although the two approaches pick out the same individuals
human beings, the way in which they ground moral status gives them
different implications for the status of human beings with radical
cognitive impairments.

The former way of grounding moral status gives it a wider
“writ,” because the individual's moral status is not
based on his relationship to specific others. Rather, it is based on
the norm of a group to which she belongs. That norm demands recognition
by anyone, whether a member of the group or not, capable of recognizing
it. If human beings with radical cognitive disabilities have full moral
status by virtue of belonging to a group with the norm of rationality,
then a rational Martian, no less than a rational human, should
recognize the full moral status of human beings with radical cognitive
disabilities. It might be possible to argue that the morally-relevant
norms of a group are not binding on those outside the group, but we
have not seen such an argument.

In contrast, ties of birth may not bind those lacking the same
biological connection; members of other species need not recognize the
full moral status of human beings with radical cognitive impairments.
In that sense, the moral status of those human beings is not as
“full” as that of other human beings, since it must be
recognized only by other humans. If full moral status is based on
duties of partiality toward members of the same group, it will be
group-relative, not binding on members of other groups.

The second type of group-based accounts acknowledges the moral
significance of the group-based attributes relied on by the first type
of group-based accounts. But accounts of the second type deny that the
full and equal moral status of human beings can be grounded in any
specific attribute, individually- or group-based, that can be described
in morally neutral terms. These accounts regard “human
being” as a thick normative concept, grounded in language and
social practice, that is not necessarily coextensive with the
biological category of “Homo sapiens,” and that has moral
content that cannot be derived from any descriptive attribute
associated with it. The judgment that a being is human and therefore
must be treated respectfully does not consist of a value-neutral
biological classification and an argument that establishes the moral
status of beings so classified. The requirement for certain kinds of
treatment, and the prohibition of others, is part of the meaning of
“human being” and implicit in discerning that a given
individual is a human
being.[9]
Proponents of these accounts thus reject the very attempt to identify a
criterial attribute possessed by all beings with the moral status of
cognitively normal human adults (Diamond 1978; Edwards 1997; Byrne
2000). These philosophers reject the treatment of cognitively
nondisabled adults as a paradigm for full moral status, and of infants,
young children, and radically cognitively disabled adults as
“marginal cases” whose moral status needs to be justified
by
extension.[10]

For both types of group-based accounts, the categorical nature of
full moral status is explained by the way in which that status is
grounded. Membership in the human species, a sufficient condition of
that status for accounts of both types, is a categorical rather than a
continuous “variable” (although there may be some vagueness
or ambiguity due to imprecise or conflicting membership criteria). And
for both types of account, the grounding of full moral status is the
same for all human beings, regardless of their individual
attributes.

5.1.1 Species Norms

On the first relational approach, some of the properties identified
by intrinsic-attribute accounts as sufficient for full moral status
play an important but distinct role. Although self-consciousness and
practical rationality are not necessary for full moral status on this
view, they are the norm for human beings. This norm cannot be
understood statistically; it would not change if most or all humans
ceased to be self-conscious or practically rational. Rather, the norm
captures what is natural to, or characteristic of the species. A normal
attribute is not, however, an essence that each member must possess.
Rather, it is a relational property: each individual has moral status
as the member of a group for which that attribute is the norm. Scanlon,
for example, claims that the class of those to whom we must justify our
actions “includes at least those beings who are of a kind that is
normally capable of judgment-sensitive attitudes” (1998,
186).

Although species-norm account focus on the human species, they are
not limited to humans. Presumably, if we discovered that dolphins or
Martians were a species with a similar cognitive norm, the individual
members of that species would possess full moral status. And they would
possess it regardless of whether they themselves had the cognitive
attributes natural to or normal for their species. We would be bound to
recognize the full moral status of all dolphins or Martians, and they
would be bound to recognize the full moral status of all humans.

There might appear to be a tension in grounding full and equal moral
status in norms to which some but not all members conform. Even if the
norm of practical rationality gives all group members equal moral
status, it might be thought that those members actually possessing that
attribute would be “more equal” than those lacking it. The
response to this concern, which we discuss in
Sec. 5.2, is that those
possessing the attribute have better fortune but no greater moral
status.

Not surprisingly, proponents of intrinsic attribute accounts, such
as McMahan, are unsympathetic with the claim that “facts about
the nature of some individuals could determine how other individuals
that lack that nature ought to be treated” (McMahan 2008, 85).
The claim he rejects seems to require that certain attributes are
“normatively characteristic of human beings—that
is, that all human beings ought to have them even if they do
not.” (85) Like other critics, McMahan sees this claim as
requiring a kind of “moral alchemy” that transmutes factual
claims about some individuals into moral demands concerning
others. For proponents of the more comprehensive views to be
discussed below, no alchemy is required. The concept of a human being
is a normative one, imposing moral demands on those who understand and
apply it.

5.1.2 (Co-)Humanity as a Special Relationship

A
second kind of species-relationship claimed to confer moral status is
not between the individual human and the species norm, but between the
individual human and other human beings, in particular, those who are
cognitively normal. The claim is that human beings have a reason, based
on co-membership in the species, to regard each other as moral equals.
As Scanlon (1998) asserts,

the mere fact that a being is
‘of human born’ provides a strong reason for according it
the same status as other humans. This has sometimes been characterized
as prejudice, called speciesism. But it is not prejudice to hold that
our own relation to these beings gives us reason to accept the
requirement that our actions be justifiable to them. (185)

This position grounds full moral status in the kinship of all human
beings—what used to be called “the family of man.”
Although this kinship currently depends on birth to a human mother, it
is shared by all human beings and does not vary with degree of
consanguinity.[11]

This approach avoids the questionable notion of a species norm as a
source of moral status. But unlike a species-norm account, it requires
no one but human beings to recognize the full moral status of all
humans. On the species norm account, McMahan (2002) observes,

intelligent and morally sensitive Martians would be required to
treat severely retarded human beings in the same way they would be
required to treat us. … But if the reason we have to
accord the severely retarded the same moral status as other human
beings is that we are related to them through the ‘tie of
birth,’ then Martians would not have this reason. (217)

This is a practically insignificant limitation at present, but an
expressively significant one for those who insist that moral status be
universally recognized.

A defender of a human kinship approach might readily accept this
limitation, especially since we and the Martians would still be
constrained by the attachments of the cognitively normal members of
the other species to their radically impaired relations (as discussed
in Sec. 4.2 above). But she would
still have to defend the claim that
co-membership in the species established the sort of kinship that
required even this species-relative full moral status. McMahan (2002)
argues that even if membership in some collectivities, like a nation,
could confer full and equal status on its members, membership in the
same species could not:

Unlike membership in a nation, membership in a species is not a
focus of collective identity. Being human does not significantly
differentiate us from anything else; it therefore fails to engage our
pride or enhance our sense of identity. Just as no one's sense of
identity is enlarged by the recognition that one is an animal rather
than a plant, so no one's sense of identity is importantly shaped
by an awareness of being human rather than being, for example, a rabbit.
(221)

The defender of a “ties of birth” account could respond
in two ways. First, she might deny that species identity and pride were
necessary to ground the full moral status of species members.
Rather, that status was grounded in similarities among
human beings, even radically disabled ones, that arose from their
distinctive embodiment and that created a strong sense of fellowship
(among those self-conscious enough to feel fellowship) overshadowing
even vast differences in mental capacity. These similarities might
include ways of feeling, communicating, moving, and reacting to and
interacting with other members of the species. These affinities are
refracted by culture, not all members of the species—even
cognitively normal ones—share all of them, and members of other
species share some of them. Nevertheless, they may be a distinctive
enough ensemble to provide a basis for partiality. Or a defender might
argue, as Bernard Williams (2006) does (see
Sec. 5.2), that
species-identity and pride could play a role in human
fellowship now obscured by the lack of a suitable comparison class.
Although, as Robert Nozick (1974) observed, no contemporary human
boasts about having an opposable thumb or speaking a language, our
sense of species pride and identity might crystallize in the presence
of another advanced species, making salient our distinctive shared
history and achievements.

Standing alone, however, both responses seem vulnerable to the claim
that similarities associated with species membership may explain, but
cannot justify, the treatment of all other human beings as moral
equals. Why should a sense of fellowship, however strong, be a source
of moral status? If our sense of fellowship reflected what mattered
morally, why wouldn't we feel greater fellowship with
McMahan's intelligent, morally sensitive Martian than with a
human infant who has severe developmental disabilities, apparently
unresponsive to other humans?

One response is that what justifies intra-species partiality is not the
capacity to share but the capacity to benefit. Thus, Gunnarson (2008)
suggests that members of our own species have a capacity to derive
unique, intrinsic benefits from their relationship to other human
beings. Reliance on such a capacity may provide an intuitively more appealing basis
for full moral status than biologically-based similarities. But it
might still deny full moral status to some humans—not only
anencephalic infants but others lacking the capacity to benefit from
relations with other humans. Moreover, some non-human animals,
especially pets, may derive benefits that are intrinsic and unique to
their relationship to human beings (Townley 2010). And the members of
other cognitively advanced species might well benefit in highly
specific, possibly unique ways, from interaction with human beings.

To explain the moral significance of species co-membership, some
philosophers embrace a strongly anthropocentric view, which denies that
we can step outside of our humanity to assess the moral status of the
world's inhabitants. On this view, the concept of a human being
is prior to, and inseparable from, that of a
person.[12]
As Stephen Mulhall
(2002) argues:

[O]ur concept of a person is an outgrowth or aspect of our concept
of a human being; and that concept is not merely biological but rather
a crystallisation of everything we have made of our distinctive species
nature. To see another as a human being is to see her as a
fellow-creature—another being whose embodiment embeds her in a
distinctive form of common life with language and culture, and whose
existence constitutes a particular kind of claim on us. (7)

This view, which, following Williams (2006), we will call
“humanist,” has two variants. The first, per Mulhall, is
linguistic or conceptual, influenced by Wittgenstein (1958). We come to
understand notions like thinking, deciding, and feeling in terms of the
behavior of other human beings, and, although we can attribute some of
these capacities or states to other beings, it is only by extension or
analogy (Hanfling 2001). We also learn the appropriate ways of acting
toward fellow human beings in learning the very concept: for example,
human beings are to be named, and not eaten even when they are dead. We
do not conclude that human beings must be treated this way;
the recognition that they must is already part of the meaning of the
concept (Diamond 1978; Gleeson
2008).[13]
This thick, normative concept of human being
is not a biological one, and need not have the same extension as the
class of Homo sapiens. For some humanists of this
type, a newly-created embryo is not a human being, and it is not part
of the meaning of human being that the life of a newly-fertilized
embryo must be protected to the same extent as the life of a newborn
human infant (Crary 2007). But the very fact that other humanists
do regard early embryos as human beings suggests the need for
an account of how such a deeply-embedded concept can be so vague or
disputable at the margins.

Because of the role of our language and concepts in our moral
understanding, the justification and criticism of our moral practices
can only be internal to them, on humanist accounts. As Byrne maintains,

reason operates in ethics properly when it functions
immanently. Offering a sound moral argument in criticism of any one
of our moral practices would be a matter of drawing upon insight from
some other part of our moral life. (2000, 70–71)

The case against eating animals,
for example, cannot be made by citing attributes they share with us,
but only by exposing tensions or contradictions with our other
practices (Diamond 1978). Presumably, similar but more acute tensions
would confront any view of humanity that excluded some biological human
beings or denied some of them full moral status, making racism and
sexism untenable without placing any pressure on the concept of
humanity itself.

The second variant denies the possibility of an impartial basis for
assessing moral status. To attempt to grade or evaluate the
world's inhabitants in absolute terms is to treat the universe as
having a point of view—the perspective of a deity or a
utilitarian Ideal Observer (Williams 2006). Without such a vantage
point, human beings can judge the rest of the world only in terms of
their own concerns, values and civilization. Our humanity thus gives us
an indispensable frame of reference for evaluating the rest of the
world. It also grounds a defensible partiality toward each other that
has little in common, structurally or morally, with racism or sexism.
Naked appeals to the humanity of another being as the basis for action
or restraint are acceptable to almost all of us; naked appeals to race
or sex, unsupported by claims about morally relevant attributes, are
rarely made by even the most unapologetic racist or sexist. The
“human prejudice” is more akin to the affinity and loyalty
of participants in a shared culture. If it is difficult to see
“the human prejudice” this way, it may be because
“[h]uman beings do not have to deal with any other creature that,
in terms of argument, principle, worldview, or whatever, can answer
back” (Williams 2006, 148). A distinctively human
“culture” is both pervasive and barely visible in a world
that offers no rivals. Williams does not claim that our commitment to
that culture would necessarily trump an appeal to participate in a more
advanced and universal community and relinquish cherished but parochial
aspects of our own culture. Nevertheless, that commitment would give us
a morally defensible reason, not just a prejudice, against such
assimilation.

Humanist accounts recognize that species norms have moral
significance, but they do not assign them the criterial role that they
play in accounts based on relational attributes in justifying the moral
status conferred by species membership. In the passage from which we
quoted earlier, Mulhall regards radically disabled humans as suffering
a grave misfortune in lacking characteristically human capacities:

We do not strive (when we do strive) to treat human infants and
children, the senile and the severely disabled as fully human because
we mistakenly attribute capacities to them that they lack, or because
we are blind to the merely biological significance of a species
boundary. We do it (when we do) because they are fellow human beings,
embodied creatures who will come to share, or have already shared, in
our common life, or whose inability to do so is a result of the shocks
and ills to which all human flesh and blood is heir—because
there but for the grace of God go I. (Mulhall 2002, 7)

For a humanist like Mulhall, the capacity to participate in
distinctively human forms of life is neither necessary nor sufficient
for full moral status (as McMahan (2005) appears to assume). That
status is established merely by our recognition of an individual as a
human being, heir to the same “shocks and ills” as we are.
Human beings with radical cognitive disabilities suffer “grave
misfortune” but not reduced status if they are not able to share
in the distinctive forms of our common life in which their embodiment
has “embedded” them. Non-human animals with similar
attributes have lower moral status but suffer no similar estrangement
or loss. Their participation in their own species' distinctive
forms of life—if there are any—does not depend upon,
and might well be impaired by, their possession of the cognitive
attributes of normal adult humans.

A critic might concede that we in fact hold these divergent attitudes
toward humans and non-human animals but would question their moral
significance: why should we regard the congenital absence of certain
capacities as a tragedy for the individual lacking them if
and only if that individual is human (McMahan 1996)? A humanist would
respond that the question itself reveals that the critic simply is not
clear on the concept of “human being”—a concept that
includes the notion of a common life, based on shared embodiment, from
which radically impaired humans are excluded.

Humanists are wary of grounding the full moral status of
radically-disabled human beings in their relationship to a species-norm
like rationality. Thus, Byrne (2000) argues that appeal to the rational
nature of human beings as the basis for respect is too reliant on
external justification and too narrow. It is too reliant on claims
about the respect owed to beings that are rational-by-nature, which
Byrne doubts are any more self-evident or plausible than claims about
the respect owed human beings. And it is too narrow because it ignores
other aspects of humanity that make the concept of “human
being” so rich and powerful.

The position of humanists on the species-relativity of moral status
is uncertain. Given the critical role they assign to “the
distinctive form of common life” of human beings for moral
recognition and obligation, it is far from obvious that Mulhall or
Diamond would require an intelligent Martian to recognize and respect
the moral status of cognitively normal human beings, let alone of human
beings with radical cognitive disabilities. Indeed, it is not clear how
humans could confidently impute intelligence to Martians if their
embodiment was sufficiently different from ours, let alone whether we
could regard them as subject to moral obligations of any kind.
Similarly, it is not clear whether Mulhall and Diamond would hold that
humans were required to treat Martians as moral equals, even if they
could attribute intelligence and moral sensitivity to them. The role
they assign to distinctively human forms of life raises doubts about
the possibility of mutual comprehension, recognition, and respect.

In contrast, Williams' account, and others less wedded to a
Wittgenstinian view of language and concepts, can more readily address
the prospect of close encounters with other intelligent beings.
Williams himself considers such encounters, and acknowledges the
possibility of mutual recognition, though he thinks it might be
reasonably qualified by partiality towards the members of one's
own species and their shared culture. Similarly, Williams would be able
to recognize the full moral status of McMahan's (2002)
Superchimp, with the intelligence of an average 10-year-old human. On
the other hand, Mulhall and Diamond might be doubtful that we would
confirm the truth of McMahan's stipulation. In any case, they
might see that chimp as tragic in his isolation from his fellow
creatures and his ill-suited embodiment—a high price to pay for
its cognitive upgrade (Kittay 2005).

Both types of humanist accounts leave critical questions about the
boundaries of the thick concept of “human being.” Does that
concept encompass early embryos, or human-like beings produced by a
future synthetic biology? Can we answer such questions in terms of the
“fit” of a proposed boundary with the other beliefs and
practices associated with the concept, or are such questions decided
less self-consciously by gradual shifts in our beliefs and
practices? Without a better sense of how boundary questions can
be resolved, it is not clear how humanist accounts will meet the
challenges of exclusion.

There seems to be little prospect for consensus on the moral status of
people with the most severe cognitive disabilities. There are sharp
disagreements about how, or even whether, the moral status of human
beings must be grounded, and about the weight to be given to our
strongest and most considered, moral convictions. Accounts that ground
full moral status in an individual's possession of specific attributes
inevitably exclude some portion of humanity, and appear to have
implications for the treatment of the excluded human beings that few
of us are willing to accept. Those implications are avoided by
accounts that ground full moral status in our species
membership—in the nature of the species or in our biological
relationships to other members. Those implications are also avoided by
accounts that deny the need to ground the moral status of human beings
in any attribute we or our group possesses. But these ways of avoiding
exclusion have significant costs. They appear to require a strong
partiality toward those with shared biological features, physical
appearances, or origins, a partiality that conflicts with equally
strong, if more abstract convictions about the justification for our
conduct towards others. And they leave deep uncertainty about the
moral constraints on our treatment of other living beings and about
the boundaries of humanity itself.

Despite the serious challenges facing both approaches, and the
formidable obstacles to reaching any sort of consensus, the discussion
about the moral status of human beings with radical cognitive
disabilities is a central one for applied ethics, and it needs to
continue.

Savulescu, J., 2009. “The Human Prejudice and the Moral
Status of Enhanced Beings: What Do We Owe the Gods?” in Human
Enhancement, J. Savulescu and N. Bostrom, eds., New York: Oxford
University Press, 211–250.